Ashley Underwood is taking advantage of the unexpected drop in mortgage rates by rushing to buy her first home before they go up again.

“I’m ready to cancel plans at a moment’s notice to go look at a house,” said Underwood, 27, who lives in Indianapolis. “I didn’t expect to see rates falling again, and I want to lock in something before I lose out.”

The drop in the last month proved forecasters wrong, said Douglas Duncan, chief economist of Fannie Mae in Washington. After the Federal Reserve announced in December that it would begin tapering purchases of mortgage-backed securities, all the major housing forecasters said rates would jump this quarter. Economists didn’t foresee that investors would react to the Fed’s retreat by moving money from emerging markets into U.S. Treasuries, driving down home-loan rates.

“I was surprised by what happened in the bond market,” Duncan said. “Everyone was surprised. It was completely unexpected that mortgage rates would fall after the Fed began tapering.”

The drop in borrowing costs means some buyers will purchase a home sooner than they had planned.

“People are getting a second chance, and that is bound to give a boost to the housing market,” said Sam Khater, deputy chief economist at CoreLogic Inc., an Irvine, Calif.-based mortgage data and software firm. “It’s not a game changer unless the emerging markets situation worsens and rates get even cheaper.”

Government-owned mortgage companies Fannie Mae and Freddie Mac, the Mortgage Bankers Association and the National Association of Realtors all forecast in January that rates would increase by at least 0.3 percentage point in the first quarter. Instead, yields on 10-year Treasuries, which are used as a benchmark for mortgage rates, shrank as investors drove up bond prices.

“The sell-off in emerging markets wasn’t expected because it was hard to measure how much they’ve relied on the Fed’s monetary policy,” said Christopher Sebald, chief investment officer for Advantus Capital Management in St. Paul, Minn., which oversees $28 billion of assets, including about $4.5 billion in mortgage bonds.

“We’re seeing the results of a herd mentality as investors exited some of the riskier corners of the world and come back to the states,” CoreLogic’s Khater said.

Janet Yellen, who took over as chairman of the central bank on Feb. 3, said in Congressional testimony yesterday that the Fed has been “watching closely” the volatility in global financial markets. She said that “our sense is that at this stage these developments do not pose a substantial risk to the U.S. economic outlook.”

Only a “notable change in the outlook” for the economy would prompt policy makers to slow the pace of tapering, Yellen said. She repeated the Fed’s statement from the conclusion of its meeting last month that asset purchases aren’t on a “preset course.”

The impact of the market rout is felt in Indianapolis, where Underwood is hunting for a three-bedroom house costing about $125,000. The drop in mortgage rates could save her about $5,000 if she stays in the house for 10 years.

“I don’t know what’s behind the fall in rates,” said Underwood, who is now a renter. “I’m looking for something I plan to be in for a long time, so getting a lower rate is going to result in a big savings.”

Cheaper borrowing costs may not be enough to increase U.S. home purchases for the year. The pace of sales probably will slow in 2014, the third year of the real estate recovery, as the 28% increase in property prices since January 2012 puts homes out of reach of some Americans.

Sales of new and previously owned homes will gain about 3.1% to 5.7 million, a third of the increase seen in 2012 and 2013, Fannie Mae’s Duncan said.

“For someone in the market to buy, it’s an opportunity to turn back the clock on rates, but there’s no indication it’s anything but a temporary reprieve,” he said. “In the long-run, the Fed’s exit means sustained upward pressure on rates.”

By the end of 2014, the average U.S. rate for a 30-year fixed mortgage probably will be 5%, Duncan said, compared with 4.3% at the end of 2013. The average during the past two decades is 6.27%, according to Freddie Mac data compiled by Bloomberg.

Borrowing costs also defied conventional wisdom the last time the Fed pulled back on stimulus. More than three years ago, when the central bank concluded its first round of quantitative easing, housing forecasters said home-loan rates would rise on weaker demand for mortgage-backed securities.

Instead, as investors fled 2010’s European sovereign-debt turmoil, loan rates tumbled to then-record lows in November. That didn’t stem the year’s plunge in home sales, which was caused by the expiration of a federal tax credit that paid buyers $8,000.

The Fed began purchasing mortgage bonds guaranteed by Fannie Mae, Freddie Mac and Ginnie Mae in January 2009 to bolster the economy and the housing market by reducing financing costs. The strategy had never been tried before. In the first round of purchases, which ended in March 2010, the Fed acquired $1.25 trillion of mortgage bonds.

The central bank announced a second round of quantitative easing, known as QE2, in November 2010. QE3 began in September 2012, with the Fed buying $40 billion of mortgage bonds and, in December, $45 billion of Treasuries a month. The central bank cut the purchases in December and again in January to $65 billion a month from $85 billion, citing an improving outlook for the labor market.

Khater, the economist, is also a home buyer who’s getting another break on rates. Even though he spends his days tracking the mortgage market, he missed 2013’s low of 3.35% in early May, the average rate as measured by Freddie Mac. That was close to the all-time low of 3.31 percent in November 2012.

“I’ve been thinking about buying, and I thought I had missed out on cheap rates,” Khater said.

The economist has intensified his search for a Washington-area single-family home, hoping to make an offer on a property in time to lock-in a mortgage rate near 4%.